Hard surface cleaners continuously evolve and adapt to customer demands, changing times, and increasingly strict health and environmental regulations. Successful hard surface cleaners can remove greasy dirt from smooth or highly polished surfaces and disinfect them without leaving behind noticeable films or streaks. Modern aqueous cleaners typically include one or more surfactants in addition to water. Commonly, the cleaners include a small proportion of low-toxicity organic solvent(s), antimicrobial agents, buffers, sequestering agents, builders, bleaching agents, hydrotropes, perfumes or fragrances, and other components.
Permanent marker is the bane of any parent of an inquisitive child. Aqueous hard-surface cleaners designed primarily for home or institutional use are mostly water and are generally ineffective in changing the appearance of markings made with permanent ink. Even solvent-based products are typically less than satisfactory in removing permanent marks from hard surfaces. Black ink is especially difficult to remove. Perhaps more insidious are the (theoretically) preventable markings of graffiti artist-vandals, who often wield permanent markers as their defacing weapons of choice.
Terpene-containing compositions such as lemon oil or pine oil are commonly found in hard surface cleaners. These compositions, which have cleaning and fragrance value, are usually complex mixtures of monoterpenes, particularly hydrocarbons, alcohols (e.g., linalool) and esters (e.g., geranyl acetate). For instance, lemon oil is about 90% monoterpene hydrocarbons, most of which is limonene, with lesser amounts of γ-terpinene, α-pinene, and β-pinene. Pine oil is also complex and species-dependent, often consisting of mostly β-pinene. Many aqueous hard surface cleaners containing lemon oil, pine oil, or other terpene-based fragrances have been described, and many are commercial products. However, the combination of terpene-based oils with fatty dialkyl amides and their use to decolorize permanent marker ink appears to be unknown.
Fatty dialkyl amides have been used in cleaners but typically in industrial applications as solvent-based degreasers for cleaning metal parts during manufacture. In one recent example (see U.S. Pat. Appl. Publ. No. 2011/0192421), the solvent-based degreaser comprises an alkyl dimethyl amide where the alkyl group has from 2 to 56 carbons. Other solvent-based degreasers include terpenes in combination with dibasic esters (see, e.g., U.S. Pat. Appl. Publ. Nos. 2009/0281012 or 2010/0273695).
Fatty dialkyl amides are typically not used in aqueous hard surface cleaners. The same can generally be said for fatty esteramines, which are more often quatemized to give esterquats that are valuable fabric softeners. Similarly, fatty amidoamines are not often used in hard surface cleaners. More often, they are oxidized to amine oxides or quaternized to other derivatives for use in laundry detergents, shampoos, or agricultural compositions.
Non-aqueous compositions are normally used for graffiti removal. Thus, e.g., U.S. Pat. No. 6,797,684 teaches to use an 80:20 mixture of d-limonene and a lactate ester to remove graffiti better than straight d-limonene. Other graffiti removers include N-methyl-2-pyrrolidone (NMP) as the principal component. See, e.g., U.S. Pat. No. 5,712,234 (NMP, a dye non-solvent, and a dye bleaching agent for permanent marker removal) and U.S. Pat. No. 5,773,091 (NMP-based graffiti remover designed for use in treating wax-coated surfaces).
Occasionally, hard surface cleaners have been formulated to contain fatty esters or amides made by hydrolysis or transesterification of triglycerides, which are typically animal or vegetable fats. Consequently, the fatty portion of the acid or ester will typically have 6-22 carbons with a mixture of saturated and internally unsaturated chains. Depending on source, the fatty acid or ester often has a preponderance of C16 to C22 component. For instance, methanolysis of soybean oil provides the saturated methyl esters of palmitic (C16) and stearic (C18) acids and the unsaturated methyl esters of oleic (C18 mono-unsaturated), linoleic (C18 di-unsaturated), and α-linolenic (C18 tri-unsaturated) acids. These materials are generally less than completely satisfactory, however, because compounds having such large carbon chains can behave functionally as soil under some cleaning conditions.
Improvements in metathesis catalysts (see J. C. Mol, Green Chem. 4 (2002) 5) provide an opportunity to generate reduced chain length, monounsaturated feedstocks, which are valuable for making detergents and surfactants, from C16 to C22-rich natural oils such as soybean oil or palm oil. Soybean oil and palm oil can be more economical than, for example, coconut oil, which is a traditional starting material for making detergents. Cross-metathesis of unsaturated fatty esters with olefins generates new olefins and new unsaturated esters that can have reduced chain length and that may be difficult to make otherwise. Despite the availability of unsaturated fatty esters having reduced chain length and/or predominantly trans-configuration of the unsaturation, surfactants have generally not been made from these feedstocks.
Recently, we described new compositions made from feedstocks based on self-metathesis of natural oils or cross-metathesis of natural oils and olefins. Among other compositions, we identified certain esteramines, fatty amides, and fatty amidoamines made by derivatizing the unique feedstocks (see Internat. Appl. Nos. PCT/US 11/57596, 11/57597, and 11/57602, respectively), all filed Oct. 25, 2011). We also investigated the use of many varieties of derivatives made from metathesis-based feedstocks in aqueous and non-aqueous hard surface cleaners (see Internat. Appl. No. PCT/US 11/57612, filed Oct. 25, 2011). In the '612 application, we observed that the fatty dialkyl amides are excellent as non-aqueous degreasers, while the fatty amidoamines and esteramines are generally inferior in that application. None of these proved to be a superior performer in the aqueous systems studied. No terpenes were present in the test formulations, and no tests were performed on permanent marker ink.
In sum, improved hard surface cleaners are always in demand. An aqueous all-purpose cleaner with the ability to decolorize permanent marker—until now just a dream—would be valuable. Ideally, the cleaner could rapidly extinguish even black permanent marks from hard, non-porous surfaces while avoiding the need for high concentrations of aggressive organic solvents. A valuable composition could be supplied as a concentrate and would complement commercially available aqueous hard surface cleaners to avoid the need to reformulate.